RINA A550 Shipbuilding Steel Coil
RINA A550 Shipbuilding Steel Coil: High-Strength Quenched & Tempered Marine Steel
Explore the detailed material data of RINA A550 shipbuilding steel coil: chemical composition, mechanical properties, and thermal properties. Equivalent grades from ABS, BV, DNV, etc. Ideal for offshore and ship structural applications.
Welding, Bending, Cutting, Machining
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RINA A550 Shipbuilding Steel Coil Introduction
RINA A550 is a high-strength, quenched and tempered shipbuilding steel grade certified by the Registro Italiano Navale (RINA). It belongs to the extra high-strength structural steels with a minimum yield strength of 550 MPa. This steel is primarily used in the construction of ships, offshore platforms, and other marine structures where high tensile properties and good toughness at low temperatures are required. The steel is supplied as coils or plates and can be processed through welding, forming, and machining. Its delivery condition is quenched and tempered (QT). RINA A550 offers an excellent combination of strength, weldability, and impact resistance, making it suitable for critical structural applications in the marine industry.
RINA A550 Shipbuilding Steel Coil Chemical Composition
The chemical composition is based on ladle analysis as per RINA rules for extra high-strength quenched and tempered steels. Limits ensure good strength, toughness, and weldability. Carbon equivalent (CE) is controlled to prevent cold cracking during welding.
| Element | Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.18 | Ladle analysis |
| Silicon (Si) | ≤ 0.50 | |
| Manganese (Mn) | ≤ 1.60 | |
| Phosphorus (P) | ≤ 0.025 | |
| Sulfur (S) | ≤ 0.025 | |
| Aluminum (Al) | ≥ 0.020 | Acid soluble |
| Niobium (Nb) | ≤ 0.05 | |
| Vanadium (V) | ≤ 0.10 | |
| Titanium (Ti) | ≤ 0.02 | |
| Copper (Cu) | ≤ 0.35 | |
| Chromium (Cr) | ≤ 0.25 | |
| Nickel (Ni) | ≤ 0.40 | |
| Molybdenum (Mo) | ≤ 0.08 | |
| Nitrogen (N) | ≤ 0.012 | Optional refinement element |
| Carbon Equivalent (CE) | ≤ 0.43 | For t ≤ 50 mm; CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
RINA A550 Shipbuilding Steel Coil Thermal and Electrical Physical Properties
These physical properties are representative for high-strength low-alloy quenched and tempered steel and are provided for engineering reference. They are not mandatory per RINA rules but are useful for design calculations. Values may vary slightly depending on actual chemical composition and heat treatment.
| Property | Typical Value | Unit | Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20°C |
| Modulus of Elasticity (E) | 205 | GPa | At 20°C |
| Shear Modulus (G) | 80 | GPa | Calculated |
| Poisson's Ratio (ν) | 0.3 | - | |
| Thermal Expansion Coefficient (α) | 12.0 × 10⁻⁶ | /K | 20-100°C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | At 20°C |
| Specific Heat Capacity | 460 | J/(kg·K) | At 20°C |
| Electrical Resistivity (ρ_e) | 0.20 × 10⁻⁶ | Ω·m | At 20°C |
RINA A550 Shipbuilding Steel Coil Mechanical Properties
The mechanical properties are verified at delivery condition (quenched and tempered). All tests are performed in accordance with RINA requirements. Impact toughness is measured with Charpy V-notch specimens at 0°C for grade A550 (longitudinal direction). For thicknesses exceeding 50 mm, slightly reduced minimum values may apply as per the standard.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 550 | MPa | Transverse, t ≤ 50 mm |
| Tensile Strength (Rm) | 670 - 830 | MPa | Transverse |
| Elongation (A) | ≥ 16 | % | Gauge length 5.65√S0, t ≤ 50 mm |
| Bend Test | 180°, d = 3a | - | a = thickness of test piece, no cracks |
| Charpy V-notch Impact Energy (KV) | ≥ 31 | J | Longitudinal, at 0°C |
RINA A550 Shipbuilding Steel Coil Exact Equivalent Materials and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | IACS UR W22 | AH550 | Common equivalent for all IACS members |
| USA | ABS Rules | AH550 | American Bureau of Shipping |
| France | BV Rules | AH550 | Bureau Veritas |
| Norway/Germany | DNV Rules | AH550 | Det Norske Veritas |
| UK | LR Rules | AH550 | Lloyd's Register |
| Japan | NK Rules | AH550 | Nippon Kaiji Kyokai |
| China | CCS Rules | AH550 | China Classification Society |
| South Korea | KR Rules | AH550 | Korean Register |
RINA A550 Shipbuilding Steel Coil Application Introduction
RINA A550 steel is extensively used in marine and offshore structures due to its high strength and excellent toughness. It can be fabricated into various components through welding, cutting, and forming processes. The steel is often supplied in coil form for further processing into plates and sections.
- Proper preheating and controlled heat input are required for welding to avoid cracking.
- Post-weld heat treatment is generally not required thanks to the quenched and tempered condition.
- It offers good fatigue resistance for dynamic loading applications.
Product Applications: Ship hulls, Offshore platform structures, Deck plates, Bulkheads, Stiffeners, Casings for heavy equipment
Processed into products: Gircers, Frames, Brackets, Floor plates, Transverse beams, Web frames, Bulkhead stiffeners, Reinforcement pads
Application industries: Shipbuilding, Offshore Oil & Gas, Marine Engineering, Port Machinery, Heavy Civil Engineering
RINA A550 Shipbuilding Steel Coil Similar and Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Italy | RINA Rules | A500 | Lower strength grade, ReH ≥ 500 MPa, similar weldability and toughness |
| Italy | RINA Rules | A620 | Higher strength grade, ReH ≥ 620 MPa, used for weight reduction |
| EU | EN 10025-6 | S550QL | Quenched and tempered structural steel with comparable mechanical properties |
Notes:
Certification by RINA is mandatory for this steel when used in classed vessels. The steel must be produced by an approved manufacturer and stamped with the RINA mark. Mill test certificates with chemical and mechanical test results are required. Hydrogen induced cracking (HIC) resistance may be ordered for sour service.
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